Animal Phenotyping

Despite numerous advances in research techniques, such as in vitro methods and advanced computer modeling which avoid the use of animals, there is still a need in preclinical research to study the morphological, physiological, metabolic or behavioral characteristics – the phenotype – of animals. Such a holistic approach to health and disease provides data that would otherwise not be available. Specifically, animal phenotyping allows researchers to gain a better understanding of the complex interactions between the cardiovascular, respiratory, and central nervous systems, which is critical for the development of many human pharmaceuticals and therapies.

Studying model animals in non-invasive ways

A comprehensive collection of tools for physiological and morphological assessment

The Animal Phenotyping Platform at the Max Delbrück Center houses a comprehensive collection of tools for physiological and morphological assessment of experimental mice and rats. We focus on techniques which minimize animal use and enable researchers to obtain comparable levels of information from fewer animals or to obtain more information from the same number of animals.

Using a wide variety of preclinical imaging techniques – such as high-frequency ultrasound, photoacoustic imaging, micro-computed tomography, quantitative bioluminescence and fluorescence imaging, and time-domain nuclear magnetic resonance imaging – allows researchers to characterize disease progression and ascertain therapeutic effects throughout the entire experimental period.

Additionally, we use various non-invasive in vivo examinations which allow physiological, metabolic, and bioelectrical variables to be monitored in conscious animals (e.g., blood pressure and heart rate measurements, electrocardiography, and respiratory analysis). We provide state-of-the-art services, innovative techniques, and helpful advice on pathophysiological questions to both experienced and novice investigators.

A holistic approach to functional genomics

Since 2020, the Preclinical Research Center (PRC) has allowed conducting of animal experiments centrally at the MDC. This new building includes enclosures housing rooms for mice, rats, and naked mole rats in direct proximity to the laboratories. We give investigators the capacity to accurately assess developmental, behavioral, cardiovascular, and metabolic characteristics in rodent disease models over long periods of time and to sensitively screen for phenotypic variations. This new structure saves the animals long transport routes and thus significantly reduces stress for the animals.

Our tools

• High-frequency ultrasound
• Photoacoustic imaging
• Micro-computed tomography (µCT)
• Magnetic resonance imaging (MRI)
• Multiphoton intravital microscopy
• Metabolic phenotyping
• Multiplex immunoassays
• Clinical chemistry
• Clinical hematology
• Hemodynamic measurements
• Body composition analysis
• Behavioral Tests
• Non-invasive electrocardiogram (ECG)
• Non-invasive blood pressure measurements
• Respiratory analysis
• Animal experiment license application support

An overview of available techniques and services:

The authorities must approve animal experiments on vertebrates and cephalopods. Therefore, considering animal welfare and the 3R principle (Replacement, Reduction, Refinement) is an essential point in our work.

We offer support in the following:

• Writing animal experiment license applications according to the legal requirements
• Writing applications in German (important for English-speaking groups)
• Development of project plans
• Finding randomization procedures
• Biometrical planning of the experiments

Writing an application for animal experiments is the first step to performing animal experiments. For inexperienced persons, this will need a lot of effort and time and thus delay the experimental progress. Writing these applications, which must be in German, is difficult enough for native speakers but even more so for non-native speakers.

The APP supports all groups of the MDC in the efficient and fast development of applications for animal experiments. In addition to the formal and legal aspects, the APP counsels the scientists in planning, calculating animal numbers, possibilities of further qualification, and exchanging know-how with other groups. Communication and drafts can be done in English. Therefore, the application is easier to manage for all English-speaking groups.

Please note that the APP cannot take responsibility for the applications. The working group qualifies the staff for the project's responsible manager and deputy manager positions.

The APP and animal welfare officers work closely to ensure the best support. Nevertheless, all applications and correspondence with the authorities must still be discussed, proofread, and submitted through the animal welfare officers. However, up to this point, the APP supports every application step.

Reduce, Refine, Replace – The 3R principle

The most important ethical principle in the performance of animal experiments is the 3Rs principle. The 3Rs principle was first published in 1959 by William Russel and Rex Burch in "The Principles of Humane Experimental Technique".

The 3Rs here stand for Replacement, Reduction and Refinement. Today, the principle is the globally accepted basis for conducting animal experiments. In the current EU Directive 2010/63/EU and its implementation in federal law in 2013, the 3Rs principle is also reflected in law for the first time. Since then, those carrying out experiments must state to what extent the 3Rs principle is or can be implemented in their applications.

Replacement involves considering whether the research question can be answered by methods other than animal testing. These can be in vitro models (cell or tissue culture), in silico methods (computer models) or body-on-a-chip methods (multi-organ chips).

However, such surrogate methods are limited in their applicability, and their use is not always possible. For example, cell and tissue cultures can only represent a tiny area of an organism. Multi-organ chips have also not yet been able to completely replace animal experiments, as only a limited number of organ models can be linked together (source: Multi-Organ-Chip - ein vollständiger Ersatz für Tierversuche?).

The complex networks that play a role in the development of diseases cannot be recreated in these models. Computer models have also been able to recreate biological processes only to a limited extent—the data on which these simulations are based on findings from animal experiments. Therefore, we often rely on in vivo experiments to study complex biological processes.

Even if animal testing cannot be replaced in many cases, alternative methods significantly reduce the stress on the animals (refinement) and the number of test animals (reduction). Numerous non-invasive test methods are available (see APP and PRC techniques). For example, in previous experiments, animals were frequently killed at specific time points to characterise and analyse disease progression. As a result, many animals were required to generate meaningful data sets. High-resolution imaging techniques such as MRI, CT or bioluminescence imaging are available for such studies today. For example, the growth of a tumour can be studied over time in the same animals, which not only increases the scientific quality of the data but also allows a very accurate assessment of the health status and stress of the animals.

For further information, please visit the 3R Website of the MDC.

PREPARE Guideline

Adrian J. Smith and colleagues developed the PREPARE (Planning Research and Experimental Procedures on Animals: Recommendations for Excellence) guideline to increase the quality and reproducibility of animal experiments and avoid repeated assessments through excellent study preparation.

The guideline is divided into three main parts:

Formulation of the study

This part includes checkpoints for the literature search, proving legal and ethical issues, performing a harm-to-benefit assessment, defining humane endpoints, and developing the experimental design and biometrical planning.

Dialogue between scientists and the animal facility

This section includes clarification of essential issues in animal husbandry. These involve questions related to occupational safety, such as those concerning contamination and resulting precautions for waste disposal. Clarification of whether special instruction is required for the employees or trial-specific particularities should also be clarified as part of this communication.

Quality control of the components of the study

This section includes the definition of all measures and courses of action that should enable high-quality work and, thus, the generation of reproducible data sets. It includes, for example, the definition of health monitoring, developing refinement measures, considerations for avoiding excess animals, and much more.

For further information and the PREPARE checklist, please visit the NORECOPA website.

References:

Smith, A.J., Clutton, R.E., Lilley, E., Hansen, K.E.A., and Brattelid, T. (2017): PREPARE: guidelines for planning animal research and testing. Laboratory animals. DOI: 10.1177/0023677217724823ontent.